The present invention relates to a method of desalinating sea water, a method of concentrating sea water (including making salt) and apparatus thereof particularly preferable in utilizing sea water sampled from deep sea (deep water) as raw materials or additives of commodities of foods, beverages, condiments, cosmetics and the like. The invention further relates to desalinated deep water and concentrated deep water (including salt) obtained by the methods. Particularly, the invention relates to methods, apparatus and products characterized in superheated steam constituting a heat source in evaporating to desalinate or condense water in sea water.
It has been carried out from ancient time to evaporate and condense to desalinate the water in sea water and providing salt by further heating remaining concentrated sea water. Further, it is a generally executed technology to use steam in heating liquid. In heating by steam, when temperature of steam for heating is not higher than boiling temperature of liquid to be heated to some degree, rapid heat conduction cannot be expected and efficient processings cannot be carried out. In evaporating the water in sea water by heating by steam, it is necessary to make temperature of steam for heating higher than the boiling point of water and therefore, pressurized steam is used. Therefore, a heating vessel or a boiler for generating steam becomes a pressure vessel and a consideration needs to be given to strength or air tightness of the vessel.
Further, deep water sampled from deep sea includes mineral contents different from those of normal sea water and therefore, there has been commercialized drinking water or cosmetics using mineral including water produced by desalinating or reducing salt of the deep water. Conventionally, as a method of desalinating or condensing deep water, there has been proposed an ion exchange method (Japanese Patent Application Laid-Open No. 2001-211864), a freezing method (Japanese Patent Application Laid-Open No. 2001-129542), an electrolysis method (Japanese Patent Application Laid-Open No. 2000-23646), or a reverse osmosis method (Japanese Patent Application Laid-Open No. 2000-354864).